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Quizzes (490) Questions (9892)

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Multiple choice reactions of haloarenes haloalkanes and haloarenes chemistry

Propane dithioic acid is prepared by which of the following reactions, followed by hydrolysis:

  1. ${C} _{3}{H} _{7}MgBr+{CS} _{2}$
  2. ${C} _{2}{H} _{5}MgBr+{CS} _{2}$
  3. ${C} _{3}{H} _{7}MgBr+{SO} _{2}$
  4. ${C} _{2}{H} _{5}MgBr+{SO} _{3}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Propane dithioic acid is prepared by the reaction of the following, followed by hydrolysis of ${C} _{2}{H} _{5}MgBr+{CS} _{2}$
Hence option B is correct.
Multiple choice reactions of haloarenes haloalkanes and haloarenes chemistry

Which of the following reaction involves copper metal?

  1. Wurtz reaction

  2. Wurtz-Fittig reaction

  3. Ullmann reaction

  4. Frankland reaction
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Wurtz & Wurtz-Fittig reactions involve Sodium (Na) metal.


Frankland reaction involves Zinc or Magnesium (Zn or Mg) metal.

Ullmann reaction involves Copper (Cu) metal.

Option C is correct.

Multiple choice reactions of haloarenes haloalkanes and haloarenes chemistry

On reacting with which of the following chemicals sulphur undergoes combination reaction?

  1. metals

  2. nonmetals

  3. acids

  4. alkalies
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

 On reacting with metals and non metals sulphur undergoes combination reaction.
$\displaystyle Fe+S \rightarrow FeS$
$\displaystyle Cl _2+2S \rightarrow S _2Cl _2$
Note:
A combination reaction (also known as a synthesis reaction) is a reaction where two or more elements or compounds (reactants) combine to form a single compound (product).

Multiple choice redox and stoichiometry applications of redox reaction oxidation- reduction reactions redox reactions chemistry

A volume of $100 ml$ of $ H _{2}O _{2}$ is oxidized by 100 ml of $ 1 M \ KMnO _{4}$ in acidic medium $ (MnO _{4}^{-}$ reduced to $ Mn^{2+}).$ A volume of $100 ml$ of same $H _{2}O _{2}$ is oxidized by $'V'$ ml of $1 M \ KMnO _{4}$ in basic medium ($ MnO _{4}^{-}$ reduced to $ MnO _{2}).$ The value of $'V'$ is

  1. $500$
  2. $100$
  3. $33.33$
  4. $166.67$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In acidic medium, 

$ N _{1}V _{1} = N _{2}V _{2} $

$ n _1\times M _{1}\times V _{1} = n _2\times M _{2}\times V _{2} $

$ 5\times 1\times 100 =  2\times M _{2} \times 100$ 

$ M _{2} = 2.5\,M $

Now in basic medium,

$ N _{1}V _{1} = N _{2}V _{2} $

$ 2\times 2.5 \times 100=  3\times 1\times V $

$ \therefore V = \dfrac{200\times 2.5}{3} $

$V = 166.66\,ml $

Multiple choice redox and stoichiometry applications of redox reaction oxidation- reduction reactions redox reactions chemistry

In a solid $AB$ of $NaCl$ structure, A atoms occupy the corners of the cubic unit cell. If all the corner atoms are removed then the formula of the unit cell will be

  1. $A _{4}B _{4}$
  2. $B$
  3. $A _{3}B _{4}$
  4. $AB$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In an NaCl structure, A atoms are at corners and face centers (total 4). If all corner atoms (8 corners * 1/8 = 1 atom) are removed, 3 A atoms remain. B atoms are at edge centers and body center (total 4). The formula becomes A3B4.

Multiple choice redox and stoichiometry applications of redox reaction oxidation- reduction reactions redox reactions chemistry

Number of electrons involved in the electrodeposition of 63.5 g of Cu from solution of $ CuSO _{4} $ is:

  1. $ 6.022\times 10^{23} $
  2. $ 3.011\times 10^{23} $
  3. $ 12.044\times 10^{23} $
  4. $ 6.022\times 10^{23} $
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
$ Cu^{2+}+2e^-\rightarrow Cu $ 

1 mole Cu = 63.5 g
 
For deposition of 1 mole of Cu, 2 moles of $e^-$ is required.

$ \therefore$ Number of electrons $ =12.044\times 10^{23} $      
                                    
Hence, option C is correct.
Multiple choice redox and stoichiometry applications of redox reaction oxidation- reduction reactions redox reactions chemistry

Write balanced half reactions for the following redox reaction:
$Cr _2O _7^{2-} + Fe^{2+}\rightarrow  Cr^{3+} + Fe^{3+}$

  1. Reduction: $6e^-+ 14H^+ + Cr _2O _7^{2-} \rightarrow Cr^{3+} + 7H _2O $

    Oxidation: $ \\ Fe^{2+} \rightarrow Fe^{3+} + e^{-}$
  2. Oxidation: $6e^-+ 14H^+ + Cr _2O _7^{2-} \rightarrow Cr^{3+} + 7H _2O $

    Reduction: $ \\ Fe^{2+} \rightarrow Fe^{3+} + e^{-}$
  3. Reduction: $4e^-+ 14H^+ + Cr _2O _7^{2-} \rightarrow Cr^{3+} + 7H _2O $

    Oxidation: $ \\ Fe^{2+} \rightarrow Fe^{3+} + e^{-}$
  4. Oxidation: $6e^-+ 14H^+ + Cr _2O _7^{2-} \rightarrow Cr^{3+} + 6H _2O $

    Reduction: $ \\ Fe^{2+} \rightarrow Fe^{3+} + e^{-}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Given Redox reaction is

$Cr _2O _7^{2-}+Fe^{+2} \longrightarrow Cr^{+3}+Fe^ {3+}$
Oxidation half reaction:- $Fe^{+2} \longrightarrow Fe^{+3}+e^-$
                                          [as oxidation number increases from $2$ to $3$]
Reduction half reaction:- $Cr _2O _7^{2-}+6e^-+14H^+ \longrightarrow 2Cr^{+3}+7H _2O$
                                          [as oxidation number decreases from $6$ to $3$]

Multiple choice redox and stoichiometry applications of redox reaction oxidation- reduction reactions redox reactions chemistry

Which particles are gained and lost during a redox reaction?

  1. Protons

  2. Neutrons

  3. Electrons

  4. Positrons
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  • Indirect redox reactions only take place if in between the electrodes is an environment that is conducive for electric current (meaning that charged particles are present that can freely move around, like the ions of dissolved or molten salts). There is no direct contact between the particles of the oxidation and the reduction. The transfer of the electrons is realised via-via, mostly via metal wiring or other conductive material. 
Exteriorly the conducting wires take care for the electron transport from RED to OX, without direct contact between the reactants.